How to understand it
Fire groups Aries, Leo and Sagittarius; earth Taurus, Virgo and Capricorn; air Gemini, Libra and Aquarius; water Cancer, Scorpio and Pisces. Each group contains cardinal, fixed and mutable modes, so members do not read alike.
An example
Use the elements to compare styles: a fire prompt may ask what motivates action while an earth prompt asks what makes that action sustainable. Neither is superior.
Use it carefully
Do not reduce a person to one element. A chart contains multiple placements and a person exceeds the chart.
Try a reflection
What style is useful for the task in front of you?